In a frontal crash, a passive safety restraint arrangement, such as airbags and/or seat belt tighteners, for example, must be triggered as soon as possible. The decision to trigger is made by using an impact sensor system, so that the decision to trigger may be made on the basis of acceleration signals as one signal of an impact sensor system. Problems have been encountered repeatedly in this regard since the acceleration signals, which are input via the chassis in the event of a misuse, for example, an incorrect triggering caused by a section of rough road, for example, or running over a curb, are at first almost identical to those which occur in the event of a crash. Triggering is often desired in the period of time during which the acceleration signals of misuse and crash are almost identical.